IN THE RAWHIDE CREEK COUNTRY of southeastern Wyoming, where you drive 50 dusty miles to post a letter, Charles and Mabel Bass are engaged in what they describe as "the hazardous occupation of dry farming." Their ranch, near Jay Em, Wyo., produces wheat, wool and mutton. For the Bases the dry Wyoming steppes yield another product that absorbs all their free time-fossil plants. For a number years they have been pursuing paleobotany at a level that has earned them world-wide recognition among professionals. Last July Earth Science, official publication of the Midwest Federation Mineralogical Societies, told about their work and credited them with many unique finds.

Their hobby got its start when Mr. Bass took to reading geological books and bulletins to beguile the time on the range while herding sheep. He thus learned something about the ground beneath his feet and developed a watchful eye or geologists, with whom he formed a quick and enduring friendship whenever any came to the region. Mrs. Bass joined him in his hobby after she exchanged the career of rural schoolteacher that of housewife, mother and part-time farmhand.

The Basses now have an impressive collection of minerals and petrified woods such as are prized by "rock hounds" everywhere. But what particularly attracts the interest of scientists is their remarkable collection of fossil seeds. An account of their work follows, in their own words.

"To put seeds in the ground," they write, "is supposed to be the principal interest of farmers. We are farmers, but for some time we have been interested in taking seeds out of the ground. The seeds that merit this unique attention are ordinary seeds of wheat or turnips or apples that you can buy at the store or find listed in the seed catalog. They seeds that have turned to stone-petrified, or what we prefer to call fossil, seeds. Our study of fossil plants and our pleasant work of collecting them is simply a hobby. Our collection includes petrified wood cut in cross sections three fourths of an inch thick and polished on one side, and lovely little limb casts showing bark structure. In the collection also are many beautiful fossil leaf-imprints of early plants and trees. Our first love, however, is the fossil seeds, which are the most interesting finds we have made in our region.

"Seeds are the final product of the flower. They are the most variable of all structures produced by plants, differing widely in surface markings, size, color and internal anatomy. These variations help botanists to classify and identify seeds even though they have been fossilized for millions of years. All seeds consist basically of two parts: the seed coat and the enclosed embryo. Some fossil seeds are still intact, and upon being broken apart or cross-sectioned show these parts very distinctly. Other fossils are merely the casts left in stone by the original seed, and they can be identified only by the seed's surface structure and markings. The complex structure of the seed parts is best studied with the aid of a microscope.

"Plants can be preserved as fossils only if they are made up, at least in part, of fibrous or woody material. All higher plants have bundles of tough, hollow, interlacing fibers, known as vascular bundles, which serve as conducting channels for food and as supporting skeletons of the plants. It is this tough substance that enables a leaf or a piece of wood to leave its imprint in rock. In the case of seeds, the hard or crustaceous outer coat is what preserves the seed in the fossilizing process.

"Organic material such as a seed is preserved from decay when it is suddenly and completely entombed beyond the reach of oxygen-by volcanic ashes, wind-blown sands, flood waters, deposits in a lake or river, peat in a bog, or some other covering material. Obviously only a very small proportion of the plants or animals which existed during any period would have been subjected to conditions that fossilized them.

"The material covering the entombed organic matter, say a seed, gradually hardens under pressure and turns to stone. Ground waters, carrying mineral matter in solution, percolate through this rock mass and remove the organic matter from the buried seed, replacing it molecule by molecule with mineral compounds. Thus the seed's exact form and minute cellular structure are preserved. In some cases the organic matter decays first and leaves a cavity in the rock the precise size and shape of the seed. Mineral-bearing ground waters then precipitate their sediments into the cavity until it is filled or partly filled with stone. This is called a cast.

"Fossil seeds are among the rarest fossils available. Reasons for their rarity are numerous. Seeds are only a short-lived stage of plant life: they normally sprout and turn into plants. Many are eaten by animals and insects. We have fossil walnut kernels showing rounded holes where worms ate into them [see photograph in Figure 3 ]. Further, seeds are less likely than leaves or branches to become petrified, because of their smallness: they are more easily crushed, decay more readily, and so on. Finally, their smallness makes them extremely difficult to find.

"In order to locate an area where fossil seeds may be found we must first know or learn something of the geologic history of the area. The first clue is the finding of some petrified wood. This may be a petrified forest or it may be only a fragment of wood eroded from a sandy bank. If the petrified forest is made up of tree trunks and branches washed into a deposit by flood waters, as is the case of the Triassic petrified forests of central Arizona, there is little use to look for fossil fruits, for they would have been lost on the journey. But if the petrified forest stands where it grew, as in some coal beds and in rock of Yellowstone Park, fossil seeds and cones are likely to be found. One of the best places to look is in stratified rock which has been eroded into cuts and gullies, exposing the strata.

"Our hunt for fossil flora takes us on many exhausting trips. Some areas are so rugged that after we have penetrated them as far as possible with a jeep or horse, the last few miles must be covered on foot. Here, and in other localities somewhat more accessible, we spend strenuous hours on hands and knees searching for tiny seeds. Some are so small they must be hunted with a magnifying glass. Some seeds, such as the walnut kernels, are found free of matrix and are ready to be brought home and immediately placed in the display case. Others, such as the pine cones, may be surrounded with hardened volcanic ash which must be tediously removed by using a small sharp instrument. The Miocene hackberry seeds, which are merely sand casts, are so soft and delicate that a chunk of the surrounding sandstone matrix must be chopped out of the cliff with a fossil pick, after which the delicate seeds are carefully removed and treated with a preservative to prevent shattering.

"For the sake of clarity and order we will group the descriptions of our fossil seeds according to the three major geologic eras in which fossil flora occur-the Paleozoic, the Mesozoic and the Cenozoic.

"We begin with the Carboniferous division of the Paleozoic era. The plants of that time are preserved today as the well-known coal-measure fossils of the Pennsylvanian, Mississippian an Permian periods. Among them we find rush-like calamites, ancient ferns and lycopods. These all reproduced by spores developed in cases on the undersides or bases of the leaves or in spore-bearing cones. The waxy and resinous outer coating of the spores helped to preserve these microscopic fossils. They are valuable to the paleobotanist in his attempt to learn about the propagation of plant life in the distant past. From this era also come evergreen relatives of our present-day conifers. Our specimens include seeds of the Cordaite trees whose woody trunks were much like those of the modern pines. The seed, about 24 millimeters long, was developed in a husk or coat, the outer layer being fleshy.

"The principal plants of the early Mesozoic era were rushes, early conifers, ferns and cycads. This is often called the age of cycads. They were the most numerous and interesting plants of this era and served as food for the dinosaurs. They had genuine flowers which developed into a seed-bearing fruit. Our collection includes several lovely cycad buds, one of which is free of matrix. Cycads were dominant until the close of the period, when the flowering plants, angiosperms, began to rise and spread. The cycads are of great scientific interest. Their series has been traced in almost continuous line from the ancient extinct species to the subtropical, palm-like plants of today.

"Our work in the Mesozoic era has been mostly among rocks of Cretaceous age. We have found objects, which a prominent paleobotanist says may be cycad seeds, within spherical accretions along with fragments of fossil wood and marine life, indicating a shoreline deposit. The seeds are about 24 millimeters in diameter and show cell structure.

"From the Cretaceous also we find the small cones of the redwood tree, the largest and oldest cone-bear evergreen. The cones are dark brown (from iron in the fossil), nearly round and from 21 to 27 millimeters in diameter. They are identified on the basis of having an average of 30 scales to a cone [see specimen at lower left in photograph in Figure 2].

"In the Upper Cretaceous rocks of Wyoming we find cones of Araucarian pines. The ovoid female cones, when broken in cross section, plainly show the seeds and the cells in which they are located. The rocks yielded casts of the fossil fig Ceratops. The specimens are remarkably figlike in appearance, and some show regular striations around the neck.

"We have in our collection seeds of the ancient ginkgo tree, Carpolithus ginkgoites fultoni. The seed is slightly obovate (with the narrow instead of the broad end at the base). It is 9 to 12 millimeters long and has longitudinal ridges. Fossil ginkgo is rare. The only species of the ginkgo tree surviving today is Gintgo biloba, a native of Japan and China.

"In the Cenozoic era the plants begin to take on a more modern aspect. The most common seeds are those of the hackberry tree, which is found in strata all the way through the Tertiary period. This tough, adaptable tree has met the challenge of the elements down through the ages in Wyoming, South Dakota and Nebraska. It must have been a prominent tree in the Cenozoic forests. Its solitary seed is cherry-like, slightly obovoid and four to six millimeters in diameter. Only the seed or pit is fossilized; the pulpy fruit has disappeared. Hackberry seeds from the Eocene stage of the Tertiary period are well preserved, but the smaller seeds of the later Oligocene are in a less perfect state, and the still later Miocene seeds are very fragile and poorly preserved in this locality. The Miocene specimens are not unlike present-day hackberry seeds.

"The very first fossil seeds we found were the kernels of Oligocene walnuts, Juglans siouxensis, which were described many years ago by the late Edward W. Berry. The Oligocene deposits in Nebraska remain our most prolific source of fossil seeds, although of course there is no such thing as an actual abundance of any fossil seed or fruit; all are scarce, and some are more scarce than others. The walnut kernels are from 15 to 18 millimeters in diameter, a golden brown in color and perfectly silicified. They look quite edible. They. show well-developed secondary lobing characteristics. We find broken pieces, quarters, halves and complete nuts, some showing part of the shell [see specimens at lower right in photograph in Figure 2].

"From the Eocene beds of the Clarno district in Oregon we have fossil seeds of walnuts, hickory, grapes and a member of the moonseed family. Other finds from the early Tertiary period, in Wyoming, Colorado and Montana, are fossil fruits of the genus Cercidiphyllum, of which the only surviving member today is the katsura tree of Japan and China. The fossil fruits are small blunted pods with seeds slightly resembling the winged seeds of a conifer.

"One of our most noteworthy finds is seeds of the Iodes, a genus of plants which still has some living members growing in the tropical regions of southeast Asia and Africa. A well-known paleobotanist informed us that lodes fossils had never before been found in North America or in beds younger than the Eocene; we found our specimens in Oligocene formations. The beautiful silicified seeds are broadly oval and lens-shaped, and their surface is ornamented with shallow concave areas.

"A number of our choice fossils are unidentified, which means that they have not been studied and given scientific names by professional paleobotonists. We, as amateur collectors, are not qualified to identify unknown specimens; consequently, no matter how closely a fossil may resemble its present-day counterpart, we must still class it as unidentified.

"Perhaps our favorite unidentified specimens are the agatized objects from the Oligocene formation of northwestern Wyoming, which look like pine cones [see object at top center of photograph in Figure 1]. They are distinctly marked with the diamond-shaped apex of the thickened cone scales, including the spots left by the recurved spines. They vary considerably in size. From the same locality we have found small unattached seeds, which we believe to be from some of these cones.

"We have some tiny, globular, pealike seeds, plainly showing the embryo, which doubtless belong to the bean family [specimens at left in middle row in photograph in Figure 1 ]. When placed beside present-day pea seeds they are as 'alike as peas in a pod.' In the Oligocene also we have found some nearly round, cherry-like seeds with the attached stem and five sepals of the persistent star-shaped calyx, as well as larger, cherry-like seeds without the calyx. Other unidentified specimens are burrlike objects which may be burrs of a chestnut or chinquapin and some lovely, perfectly preserved catkins [at top in photograph in Figure 2]. We suspect that some, if not all, of the unidentified finds are new to science and are deserving of description in scientific literature.

"As long as there are more fossil seeds, woods or leaves to be found, we intend to keep on looking for them. We would love to find an acorn or a cone or fruit different from any other ever found, and this we will do unless old age overtakes us too soon. We sometimes wonder if paleobotany has been given its rightful place in the study of the science of living things. Extensive searches have been carried on for fossil animals, but plants are just as important, for without plants there would have been no animals.

"We have never regretted choosing this hobby-or perhaps we should say that it chose us. If you ever begin to pay attention to fossil flora, you will find the interest growing on you like a coat of tan on a summer day. Once you have found the specimen that is one in a million, once you have seen through a magnifying glass the intricate perfection of a tiny agate seed or the delicate cell structure of a piece of replaced wood, you will give your heart to this fascinating pastime. Such a hobby, like beauty, is its own excuse for being. It is pregnant with the diligence of study, the dignity of labor, the thrill of discovery, the pride of possession and the pleasure of sharing.

"Trees of the ancients,
plants of the past,
Fruit of the gods,
leaves that will last,
Catkins of agate, flowers
of stone,
Silica walnuts, agate pine cone,
Seeds of the Iodes,
tropical vine,
Have lain in the mud
through ages of time.
Seeds of the hackberry,
others I've found,
Lie in my case on velvet
background.
These are the essence of
nature's springtime,
God has preserved them,
now they are mine."

Roger Hayward, whose drawings regularly adorn this department, enjoys tinkering with devices for demonstrating basic mechanical principles. Recently he confected two versions of a rubber-band heat engine, with the object of showing how a system becomes increasingly sensitive to external forces as it approaches the condition of stability.

"One easy way to demonstrate this," he writes, "is to consider the case of two cylinders of unequal diameter standing on end. It takes less force to push over the thinner cylinder. The narrower cylinder, the closer it comes to the condition of instability.

"With a few rubber bands, a needle, some thread and other household objects, you can devise heat engines demonstrating this principle in more interesting ways. I propose to illustrate two systems here.

"The first [Figure 4 ] is based on a classical seismometer scheme. From a bracket, which can be a laboratory glassware holder, a piece of aluminum foil is suspended on a thread. The foil, or bob, can pivot around its midpoint, which is attached to a stretched rubber band. The aluminum foil is curled up at the edge to shade the rubber band from a desk lamp that shines on it.

"Turn the bob to the left. The left side of the rubber band is now unshaded. Warmed by the lamp, this part of the rubber shrinks, i.e., contracts. The pivot point accordingly moves slightly to the left. As a result the pendulum now swings to the right. The curled portion of the bob then shades the warmed portion of the band and exposes the other half to the lamp. The opposite half of the cycle then begins. The apparatus, as here proportioned, will vibrate about 16 cycles per minute over an amplitude of about 10 degrees. I tried observing the shift of the bottom pivot with a small telescope. The motion must be less than a thousandth of an inch, because it was not perceptible.

"Save for the leveling screws, which must be capable of exquisite adjustment, the rest of the apparatus is easy to make. Aluminum foil for the bob is easy to cut with ordinary scissors. The 24-gauge weight of foil used for bakery pie-plates is handy. The vane or bob is balanced on the thread by sliding the washers toward or away from the thread. This is quite easy. A wooden structure can be substituted for the lab stand. The thread is N.Y.M.O. sewing thread size A, 300 yards per spool.

"Aside from the stability effects, I suppose the two lessons to be learned from this experiment have to do, first, with the phase relationships of the system, and second, with the surprising behavior of rubber when subjected to changes in temperature. The driving force for any oscillator must be out of phase with the displacement, preferably by 90 degrees. In the case of the 'figure 4' seismometer suspension, the inertia of the pendulum plus the time lag in warming the rubber combine to approximate 90 degrees. As for the behavior of warmed rubber, one would suppose that it should expand with increasing temperature like almost everything else. It does-except when under tension. I discussed this with Linus Pauling some years ago and he said that you should picture rubber, when under tension, as a bundle of stretched chains, with heat shaking the chains. The harder the chains are shaken (by thermal agitation) the more they pull on the fastenings at their ends. Thus the rubber can have either a positive or negative temperature coefficient, depending on how you use it-a property which suggests endless experiments.

"As far as I know this peculiar form of pendulum, as driven by rubber, is new; at least I worked it out myself last night after I went to bed. It might be used as a thermometer, and measure temperature mixed with earthquakes. Moral: It is easy to make any device sensitive if you don't care how many things you measure simultaneously. But if the gadget is to unscramble the mixture, then it is harder to make.

"The second system [Figure 5] shows the same principle applied to a gadget which converts heat into rotary motion. The rim of the wheel is cut from corrugated cardboard with a sharply pointed knife. The rim supports spokes made of rubber bands, and they in turn hold a needle shaft in alignment. You mount this assembly between two plates of thin tin or aluminum. I had the engine running in about an hour, the first 40 minutes being spent in getting the needle to stay in proper alignment. Equalizing the tension on the two sides of the wheel is quite a chore. The needle ends to turn sideways and dump off the bands. Then you start all over. You must next adjust the bands until the wheel balances perfectly when in its bearings. The balancing act, however, is not too difficult. If the wheel persists in coming to rest with an unbalanced section down, you move the outer tips of the bands until it is balanced all around. Now you shine a 50-watt lamp close to one side of the shield. The wheel will start rotating at seven revolutions per minute. The gadget ran all evening.

"For the upcoming generation who would like a wheel intended to run forever without an external source of power, we submit the classical perpetual motion machine shown in the upper-left corner of the drawing. The principle: Sixes become nines as the wheel turns. Whether this numerical increase can generate counterclockwise rotation I leave to you."

Many readers have called our attention to an error in the legend of the circuit diagram which appeared at the top of page 134 in the February issue. The resistance value should have been 560,000 ohms, not 560.

Bibliography

GEOLOGY. O. D. von Engeln and K. E. Caster. McGraw-Hill Book Company, Inc., 1951.

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